KR20020057959A - Crosslinkable compositions of functionalised polyolefin powders - Google Patents

Abstract

The present invention provides a particle size from 100 to 20, formed from functionalized polyolefin powders comprising functionalized polyolefins (A) having a MFI of at least 20 (190 ° C 2.16 kg), products (B) having a role of crosslinking (A). It relates to a 400 μm crosslinkable composition. The compositions are useful for slush molding, thermoforming of sheets, or injecting on inserts.

Description

Cross-linkable composition of functionalized polyolefin powder {CROSSLINKABLE COMPOSITIONS OF FUNCTIONALISED POLYOLEFIN POWDERS}

Automotive dashboards are often covered with a PVC shroud made of polyurethane and obtained by the slush molding process. The use of PVC is becoming less possible because of the risk of contamination from combustion. Therefore, it is necessary to develop a polyolefin shell. Polypropylene shells have already been disclosed in the prior art, but they do not have sufficient durability at high temperatures that can be found in outdoor sunny areas and in vehicles with closed windows, and the durability is measured by hot creep.

Patent FR 2,721,319 discloses a powder composition for slush molding described on polypropylene and ethylene-propylene rubber (EPR). The obtained shell has no good creep resistance.

The present invention relates to crosslinkable compositions formed from functionalized polyolefin powders that can be used in a slush molding method or to thermoforming or injection molding into inserts, and more particularly to compositions based on functionalized polyethylene.

The outer shell is obtained by a molding method (hereinafter referred to as a slush molding method) by free flowing of the powder on a hot mold using PVC or polyolefin powder. Slush molding is used in the manufacture of outer panels for dashboards, door panels and consoles in the automotive sector. The powder is contacted with a hot mold, for example by a free flow technique, so that the powder forms a shell by melting. The shell feels very soft and free of residual stresses, which can avoid the risk of crack appearance caused by residual stress relaxation during aging of the shell.

Polyolefin powder compositions that can be used in slush molding, thermoforming of sheets or injection molding into inserts and are thus found to be crosslinkable, have now been found, yielding good wear resistance and good creep resistance. Thus, the present invention is a crosslinkable composition having a particle size of 100 to 400 μm, formed from a functionalized polyolefin powder comprising:

Functionalized polyolefins (A) having an MFI of at least 20 (190 ° C./2.16 kg), containing anhydrides and / or epoxy functional groups,

Product (B) which has a role of crosslinking (A).

In a first embodiment of the invention, (A) is selected from the copolymer of ethylene and unsaturated carboxylic anhydride and (B) is selected from the copolymer of ethylene and unsaturated epoxide.

In a second embodiment of the invention, (A) is selected from the copolymer of ethylene and unsaturated carboxylic anhydride and (B) is selected from the polyamine adsorbed on the zeolite.

In a third embodiment of the invention, (A) is selected from copolymers of ethylene and unsaturated epoxides and (B) is selected from polyamines adsorbed on zeolites.

In the slush molding method, the composition of the present invention is converted into an outer plate upon contact with a mold. For example, crosslinking occurs at a temperature above the melting point of (A) when carried out with the outer shell in the mold as in the three embodiments mentioned above. For example, in the second and third embodiments, if moisture is selected to derive the amine from the zeolite after formation of the shroud, if the crosslinking is subsequently initiated by the method of diffusion of moisture through the shroud, from room temperature to (A) Crosslinking occurs at the softening point.

For the first embodiment, copolymer (A) can be polyethylene grafted with unsaturated carboxylic anhydride or a copolymer of ethylene with unsaturated carboxylic anhydride, for example obtained by radical polymerization.

The unsaturated carboxylic anhydride is, for example, maleic anhydride, itaconic anhydride, citraconic anhydride, allylsuccinic anhydride, cyclohex-4-ene-1,2-dicarboxylic acid anhydride, 4-methylenecyclohex 4-ene-1,2-dicarboxylic acid anhydride, bicyclo [2.2.1] hept-5-ene-2,3-dicarboxylic acid anhydride and x-methylbicyclo [2.2.1] hept- 5-en-2,2-dicarboxylic acid anhydride can be selected. It is advantageous to use maleic anhydride. Replacing all or part of the anhydride with unsaturated carboxylic acids, such as (meth) acrylic acid, would not be beyond the scope of the present invention.

With respect to polyethylene for grafting unsaturated carboxylic anhydride, " polyethylene " is understood as a homopolymer or copolymer.

As comonomers, mention may be made of:

Advantageously α-olefins having 3 to 30 carbon atoms; Examples of the α-olefins are propylene, 1-butene, 1-pentene, 3-methyl-1-butene, 1-hexene, 4-methyl-1-pentene, 3-methyl-1-pentene, 1-octene, 1 -Decene, 1-dodecene, 1-tetradecene, 1-hexadecene, 1-octadecene, 1-eicosene, 1-docosene, 1-tetracosene, 1-hexacosene, 1-octacosene and 1- Triaconten may be mentioned; The α-olefins may be used alone or as a mixture of two or more thereof,

Unsaturated carboxylic acid esters, for example alkyl (meth) acrylates in which the alkyl may have up to 24 carbon atoms; Examples of alkyl acrylates or methacrylates are especially methyl methacrylate, ethyl acrylate, n-butyl acrylate, isobutyl acrylate or 2-ethylhexyl acrylate,

Vinyl esters of unsaturated carboxylic acids, for example vinyl acetate or propionate,

Dienes, for example 1,4-hexadiene,

Polyethylene may comprise several species of such comonomers.

Polyethylene, which may be a blend of several polymers, advantageously comprises at least 50% and preferably 75% (mol) of ethylene and the density thereof may be between 0.86 and 0.98 g / cm ³ . MFI (viscosity index at 190 ° C./2.16 kg) is advantageously between 20 and 1000 g / 10 min.

As examples of polyethylene, mention may be made of:

Low Density Polyethylene (LDPE)

High Density Polyethylene (HDPE)

Linear Low Density Polyethylene (LLDPE)

Ultra low density polyethylene (VLDPE),

Ethylene and α-olefins, such as propylene, butene, hexene, in the presence of polyethylene, i. Or a polymer obtained by copolymerization of octene. More particularly, the metallocene catalyst is usually composed of two cyclopentadiene rings bonded to the metal. Such catalysts are often used with aluminoxanes, preferably methylaluminoxanes (MAO), as cocatalysts or activators. Hafnium may also be used as the metal to which cyclopentadiene is attached. Other metallocenes can include transition metals from groups IVA, VA, and VIA. Lanthanide series metals may also be used.

-EPR (ethylene-propylene rubber) elastomer

EPDM (ethylene-propylene-diene) elastomers

Blends of polyethylene and EPR or EPDM

Ethylene / alkyl (meth) acrylate copolymers containing up to 60% by weight and preferably from 2 to 40% by weight of (meth) acrylate as possible.

Grafting is known per se.

For those which do not graf copolymers of ethylene and unsaturated carboxylic anhydrides, ie unsaturated carboxylic anhydrides, these are the comonomers mentioned above in the case of ethylene, unsaturated carboxylic anhydrides and ethylene copolymers to be grafted. Copolymers of any other monomer that may be selected from.

Advantageously, ethylene / maleic anhydride and ethylene / alkyl (meth) acrylate / maleic anhydride copolymers are used. The copolymer comprises 0.2 to 10% by weight of maleic anhydride and 0 to 40% by weight and preferably 5 to 40% by weight of alkyl (meth) acrylate. Its MFI is 20 to 100 (190 ° C./2.16 kg). Alkyl (meth) acrylates are already described above. Melting point is 80-120 degreeC.

Copolymer (A) is compatible and prepared by radical polymerization at a pressure that can be from 200 to 2500 bar. Sold in the form of granules. Microgranules can be powdered using, for example, the water cutting technique of company Gala (Virginia, USA) or by cryogenic grinding.

For (B), ie copolymers of ethylene and unsaturated epoxides, they can be obtained by copolymerization of ethylene and unsaturated epoxides or grafting of unsaturated epoxides on polyethylene. Grafting can be carried out in molten polyethylene in the solvent phase or in the presence of peroxides. The grafting technique is known per se. For the copolymerization of ethylene and unsaturated epoxides, one can use the method referred to as the radical polymerization method which normally operates at 200 to 2500 bar pressure.

As examples of unsaturated epoxides, mention may be made of:

Aliphatic glycidyl esters and ethers such as allyl glycidyl ether, vinyl glycidyl ether, glycidyl maleate, glycidyl itaconate and glycidyl (meth) acrylate, and

Alicyclic glycidyl esters and ethers such as 2-cyclohexene-1-glycidyl ether, diglycidyl cyclohexene-4,5-carboxylate, glycidyl cyclohexene-4-carboxylate, Glycidyl 5-norbornene-2-methyl-2-carboxylate and diglycidyl endo-cis-bicyclo [2.2.1] hept-5-ene-2,3-dicarboxylate.

For grafting, a copolymer is obtained from the grafting of the polyethylene homopolymer or copolymer as described for (A), except that the epoxide is grafted instead of anhydride. For copolymerization, it is also similar to (A) except using epoxide. As in the case of (A), other comonomers can also be.

Product (B) is advantageously an ethylene / alkyl (meth) acrylate / unsaturated epoxide copolymer. It may advantageously contain up to 40% by weight, preferably 5 to 40% by weight of alkyl (meth) acrylate, and up to 10% by weight, preferably 0.1 to 8% by weight of unsaturated epoxide.

Epoxides are advantageously glycidyl (meth) acrylates.

The alkyl (meth) acrylate is advantageously selected from methyl (meth) acrylate, ethyl acrylate, n-butyl acrylate, isobutyl acrylate or 2-ethylhexyl acrylate. The amount of alkyl (meth) acrylate is advantageously 20 to 35%. MFI is advantageously 5 to 100 (g / 10 min, 190 ° C./2.16 kg) and a melting point of 60 to 110 ° C. The copolymer can be obtained by radical polymerization of monomers. The powder formation method is performed as in (A).

If the composition comprises several polymers (A) and / or several polymers (B) it will not be outside the scope of the present invention (this applies to all embodiments).

For the fractions of (A) and (B), this is advantageously to the extent of 0.1 to 1.5 (preferably 0.2 to 0.6) anhydride functional groups per epoxide functional group. It is advantageous to use catalysts, ie products which can facilitate the reaction between anhydride functional groups and epoxide functional groups. The catalyst acts directly from the melting of (A) and (B) to be similar. The fraction of catalyst can be readily determined by one skilled in the art, and the reaction between anhydrides and epoxide functional groups is known per se. Crosslinking is advantageously carried out by heating the mold at a temperature above the melting point of (A).

Among the compounds capable of catalyzing the reaction between the epoxy functional groups present in (B) and the anhydride functional groups present in (A), mention may be made in particular of:

Tertiary amines such as dimethyllaurylamine, dimethylstearylamine, N-butylmorpholine, N, N-dimethylcyclohexylamine, benzyldimethylamine, pyridine, 4-dimethylaminopyridine, 1-methylimidazole, Tetramethylethylhydrazine, N, N'-dimethylpiperazine, N, N, N ', N'-tetramethyl-1,6-hexanediamine or tertiary amine with 16 to 18 carbon atoms known by name Mixture of

Tertiary phosphines such as triphenylphosphine,

Zinc alkyl dithiocarbamates,

Acids, such as polymers such as LUCALEN (ethylene / butyl acrylate / acrylic acid terpolymer),

Mixtures containing magnesium salts such as 65% stearate salt and 35% palmitate salt.

For the second embodiment of the invention, the functionalized polyethylene (A) has already been described in the first embodiment. (B) is a polyamine adsorbed on zeolite, and under temperature synergism, the polyamine desorbs and crosslinks (A). It is sufficient to select a polyamine / zeolite pair so that desorption occurs above the melting point of (A). Desorption also occurs with water or moisture, which is why it is recommended to add to the zeolites filled with polyamines other zeolites which can adsorb moisture to prevent crosslinking during storage. Such crosslinking techniques of zeolites which release polyamines under temperature or moisture action and polymers comprising carboxylic acid anhydride groups are disclosed in US Pat. No. 5,792,816, the content of which is incorporated herein.

As examples of polyamines, mention may be made of: ethylenediamine, propanediamine, butanediamine, pentanediamine, hexanediamine, isomers of these amines, 1,2-diaminocyclohexane, 1,4-diaminocyclohexane, Diethylenetriamine, triethylenetetraamine, tetraethylenepentaamine, 3-[(N-aminoethyl) amino] propyltrialkoxysilane, triaminopropyltrialkoxysilane, piperazine, aminoethylpiperazine, diaminoethylpipe Razin, xylylenediamine, isophoronediamine, 3,3'-dimethyl-4,4'-diaminocyclohexylmethane or 1,4-diaminobenzanilide. Some of the polyamines may be replaced with polyols or aminoalcohols such as: ethylene glycol, propylene glycol, triethylene glycol, dipropylene glycol, butanediol, neopentyl glycol, cyclohexane-dimethanol, hydroquinone bishydroxyl ether, triethanol Amines, methyldiethanolamine, tripropanolamine, N, N-di (2-hydroxyethyl) aniline, ethanolamine, diethanolamine, propanolamine, dipropanolamine and N- (hydroxyethyl) aniline. For zeolites, advantageously ones having a pore diameter of 0.3 to 1.5 nm and preferably zeolites selected from the following four (indicative of the pore diameter) are used:

0.38 nm, designated as type 4A,

0.44 nm, designated as Type 5A,

0.8 nm, specified as a 10X type,

0.84 nm, specified as type 13X.

All these zeolites are available in particle sizes on the order of 20-50 μm. In addition to the polyamine, the zeolite may be charged with a catalyst for the reaction of anhydrides and amines. Various examples of desorption temperatures are provided below:

Zeolite A Min Desorption Temperature (℃) 4A Ethylenediamine 175 +/- 5 4A Ethanolamine 175 +/- 5 13X Ethylenediamine 130 +/- 5 13X Ethanolamine 125 +/- 5 13X Diethylenetriamine 125 +/- 5 13X Piperazine 120 +/- 5

Once the shell is formed, crosslinking can be effected by heating above the melting point of (A) or subsequently the shell is removed from the mold by diffusion of ambient moisture at temperatures between room temperature and the softening point of (A).

For the third embodiment of the invention, it is the same as the second embodiment but replaces the copolymer of ethylene and carboxylic anhydride with the copolymer of ethylene and epoxide. The copolymer has already been described as polymer (B) in the first embodiment. This is sufficient if you have an MFI of 20 or more.

The grafting reaction is carried out in a single or twin screw extruder in which the polyolefin is fed from the feed hopper, for example in the form of granules. The polyolefin is melted by heating in the first zone of the extruder and the reactants are introduced into the melt of the polyolefin in the second zone.

The radical initiator can be selected from peroxides, peracids, peresters and peracetals. Usually, these are used in amounts of 0.01% by mass to 0.5% by mass relative to the grafted polyolefin.

Compositions of the present invention may also include anti-coating agents such as silica AEROSIL R972, processing aids such as ethylene bis (stearicamide), mold release agents such as calcium stearate or magnesium stearate, and other components such as sticky resins such as resin REGALITE R1115 Can be.

Also process stabilizers such as IRGAFOS 168, DDPP, P-EPQ, TNPP, TPP, PS 800 and PS 802, antioxidants such as IRGANOX 1010, 245, 259, 565, 1035, 1076, 1098, 1135, 1141, 1330, 1425 , 3052, 3114, 5057 and M1024, mixtures of antioxidants and processing stabilizers such as IRGANOX B225, and UV stabilizers such as Ciba from TINUVIN and CHIMASSORB.

It may also include fillers and colored pigments such as carbon black and TiO ₂ .

It may also include deodorants such as activated carbons such as 3S, CXV (CECA), undecylenic acid, ethyl undecylenate, calcium undecylenate, zinc undecylenate cyclodextrin, zeolites such as FLAVITH, and fragrances.

The outer shell is formed by melting the powder blends (A) + (B) on a hot mold, followed by crosslinking by removing excess unmelted powder and then leaving the outer shell in an oven at 200 to 350 ° C. for 10 seconds to 10 minutes. May continue or start. The shell is then cooled and separated from the mold. In addition, in the second and third embodiments, it is possible to remove the shell from the mold and crosslink it with moisture.

The composition of the present invention is capable of obtaining an outer shell that is very soft to the touch, has a Shore A hardness of less than 90 and exhibits no creep when hot without the use of a liquid plasticizer. The shell advantageously has the following characteristics:

Thickness is from 0.6 to 1.1 mm

-Tensile strength (TS) is at least 5 MPa

-Elongation at break (EB) is more than 300%

Aging is less than 40% after 500 hours at 100 ° C, expressed as a change in elongation

Aging is 50% or less after 250 hours at 120 ° C., expressed as a change in elongation at break

Aging is less than or equal to 10% after 250 hours at 120 ° C., expressed as a rate of change in tensile strength

Elongation after creep at 140 ° C under a load of 0.5 bar

-Fogging, DIN 75201 (3 hours at 100 ° C): no adhesion (measurement of phthalate movement)

Wear and grinding wear after 30 minutes: meets standard requirements

-Gloss: meets standard requirements

Heat resistance (22 hours at 100 ° C): meets standard requirements.

Except where otherwise indicated, the composition (% of acrylate, etc.) and the composition of the powders of the present invention are by weight.

The following product is used:

Ethylene / methyl acrylate / glycidyl methacrylate (GMA) copolymer containing LOTADER® 8900, 28% acrylate and 7.8% GMA and having MFI of 6;

Ethylene / ethyl acrylate / maleic anhydride (MAH) copolymer containing LOTADER® 6660, 27.5% acrylate and 2.9% MAH, with MFI of 40;

Ethylene / ethyl acrylate / maleic anhydride (MAH) copolymer containing LOTADER® 7500, 20.0% acrylate and 3.0% MAH and having an MFI of 70;

Ethylene / butyl acrylate / glycidyl methacrylate (GMA) copolymer containing LOTADER® AX 8999, 28% acrylate and 1% GMA and having an MFI of 70;

Dimethyl tallowamine (DMTA) in the form of 3% masterbatch in ethylene / butyl acrylate / MAH copolymer with XX 1275, catalyst, 32% acrylate and 3% MAH, with MFI of 7;

Ethylene / butyl acrylate / acrylic acid copolymer containing LUCALEN A3110M, 8% acrylate and 4% acrylic acid and having an MFI of 6-8 (190 ° C., 2.16 kg);

IRGANOX B 225, 1: 1 IRGANOX 1010 / IRGAFOS 168;

TACKIFYING RESIN, REGALITE R1125;

MM, carbon black;

A mixture of MAGNESIUM STEARATE, 65% stearate salt and 25% palmitate salt;

AEROSIL R972 (Degussa);

ACTIVE CARBON, 3S and CXV (CECA).

Various components are reduced to a powder of particle size 200 μm by cryogenic milling.

Various compositions of the present invention are prepared by blending the ingredients in a powder blender. The outer plate is manufactured by the slush molding technique. The mold is raised to 250 ° C. in an oven. The mold removed from the oven is subsequently coated with excess powder of the composition used. After about 10 seconds, the unmolded powder is removed by overturning the mold. The mold is then raised to 250 ° C. again in the oven for 3 minutes. The mold is subsequently cooled in cold water. The shell is subsequently removed from the mold. Compositions and physical properties are shown in Table 1 below.

Examples 5 and 6

Example 5 is a black shell and Example 6 is a gray shell. This example provides better performance, better heat aging resistance (antioxidant) and odor reduction (activated carbon) than Examples 1 and 4 in terms of wear, mechanical properties, toxicity (no dimethylsulphamine).

The preparation of the powder is divided into various stages. The preparation is the same for all formulations.

1.Formulation of formulations described in LOTADER 8900 (= A) and LOTADER 7500 (= B) (Example 5)

Formula A below is drawn off while blending in a Leistritz twin screw extruder at 160 ° C., and formulation B is drawn out while blending in a Leastritz twin screw extruder at 180 ° C. FIG.

Example 5 (black) Formulation A (part) Formulation B (part) LOTADER 8900 96.0 - LOTADER 7500 - 68 REGALITE R1125 Resin 2.0 2.0 IRGAFOS 168 0.4 0.4 IRGANOX 1010 1.0 1.0 MM, carbon black 1.0 1.0 LUCALEN M 3110 - 28.0 Activated carbon 3S 1.0 1.0 Activated Carbon CXV 1.0 1.0

2. Dry blend of granules of two components in the specified fraction

A and B granules are dry blended with an A / B mass ratio = 1.575.

3. Preparation of powder by cryogenic grinding and mixing of additives

The formulation is then cryogenically ground to a powder of 200 μm particle size and 2% magnesium stearate and 0.6% AEROSIL silica are added to the high speed mixer.

4. Slush Molding

The mold is treated with a release agent at 100 ° C., heated at 120 ° C. for 20 minutes (Chem-Trend S.A. Mono Coat MC-708A) and raised to 250-300 ° C. in an oven. The mold removed from the oven is then coated with a powder excess of the composition used. After about 10 seconds, the undissolved powder is removed by overturning the mold. The mold is then heated again in the oven at 250-300 ° C. for 1-5 minutes. The mold is then cooled in cold water. The shell is then removed from the mold.

The composition and physical properties of the formulations of Examples 5 and 6 are as follows:

compound Example 5 (black) (part) Example 6 (gray) (part) LOTADER 8900 55.7 54.6 LOTADER 7500 26.3 26.3 LUCALEN M 3110 10.8 10.1 IRGANOX 1010 One - IRGAFOS 168 0.4 - IRGANOX B225 - One REGALITE R1125 Resin 2 2 TiO ₂ 2.9 Activated carbon 3S 1.0 1.0 Activated Carbon CXV 1.0 1.0 MM, carbon black One 0.3 Addition by dry blending Magnesium stearate 2 2 AEROSIL R 972 0.6 0.6 Properties Tensile strength (MPa) > 6 > 6 Elongation at Break (%) > 300 > 300 Creep 0.5 bar (min) 140 ℃ > 30 > 30 % Change in elongation at break after aging (250 hours at 120 ° C) <50 <50 % Change in tensile strength after aging (250 hours at 120 ° C) <10 <10 Spray degree, DIN 75201 (3 hours at 100 ° C) No attachment No attachment

Example 1 Example 2 Example 3 Example 4 Example 5 Example 6 LOTADER 8900 34.8 34.8 24.4 28.4 17.4 LOTADER 6600 63.2 18.8 63.2 49.9 51.6 41 LOTADER AX 8999 79.2 23.7 39.6 XX 1275 2 2 2 2 Loss (g), Taber Test 0.0075 / 0.018 0.0196 Average loss (g), tape test 4.6 Standard deviation of loss 4.0 Post-smoothing at 250 ° C Creep resistance at 120 ° C without load for 3 minutes 30 minutes 30 minutes 30 minutes

Claims (7)

A crosslinkable composition having a particle size of 100 to 400 μm, formed from a functionalized polyolefin powder comprising: Functionalized polyolefins (A) having an MFI of at least 20 (190 ° C./2.16 kg), containing anhydride and / or epoxy functional groups; Product (B) which has a role which crosslinks (A). The composition of claim 1, wherein (A) is selected from the copolymer of ethylene and unsaturated carboxylic anhydride and (B) is selected from the copolymer of ethylene and unsaturated epoxide. 3. A method according to claim 2, wherein (A) is selected from ethylene / alkyl (meth) acrylate / maleic anhydride copolymers, wherein the copolymer is 0.2 to 10 wt% maleic anhydride and 5 to 40 wt% alkyl ( A composition comprising meth) acrylate. 4. Ethylene / alkyl (meth) acrylic according to claim 2 or 3, wherein product (B) may advantageously contain up to 40% by weight of alkyl (meth) acrylate and up to 10% by weight of unsaturated epoxide. The composition is a rate / unsaturated epoxide copolymer. The composition of claim 1 wherein (A) is selected from copolymers of ethylene and unsaturated carboxylic anhydrides and (B) is selected from polyamines adsorbed on zeolites. The composition of claim 1 wherein (A) is selected from copolymers of ethylene and unsaturated epoxides and (B) is selected from polyamines adsorbed on zeolites. A method for producing an article that is molded by slush molding, comprising melting and then crosslinking the composition according to any one of the preceding claims.